gecko/accessible/base/AccessibleOrProxy.h

122 lines
2.6 KiB
C++

/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* vim: set ts=2 et sw=2 tw=80: */
/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
#ifndef mozilla_a11y_AccessibleOrProxy_h
#define mozilla_a11y_AccessibleOrProxy_h
#include "mozilla/a11y/Accessible.h"
#include "mozilla/a11y/ProxyAccessible.h"
#include "mozilla/a11y/Role.h"
#include <stdint.h>
namespace mozilla {
namespace a11y {
/**
* This class stores an Accessible* or a ProxyAccessible* in a safe manner
* with size sizeof(void*).
*/
class AccessibleOrProxy
{
public:
MOZ_IMPLICIT AccessibleOrProxy(Accessible* aAcc) :
mBits(reinterpret_cast<uintptr_t>(aAcc)) {}
MOZ_IMPLICIT AccessibleOrProxy(ProxyAccessible* aProxy) :
mBits(reinterpret_cast<uintptr_t>(aProxy) | IS_PROXY) {}
MOZ_IMPLICIT AccessibleOrProxy(decltype(nullptr)) : mBits(0) {}
bool IsProxy() const { return mBits & IS_PROXY; }
ProxyAccessible* AsProxy() const
{
if (IsProxy()) {
return reinterpret_cast<ProxyAccessible*>(mBits & ~IS_PROXY);
}
return nullptr;
}
bool IsAccessible() const { return !IsProxy(); }
Accessible* AsAccessible() const
{
if (IsAccessible()) {
return reinterpret_cast<Accessible*>(mBits);
}
return nullptr;
}
bool IsNull() const { return mBits == 0; }
uint32_t ChildCount() const
{
if (IsProxy()) {
return AsProxy()->ChildrenCount();
}
return AsAccessible()->ChildCount();
}
/**
* Return the child object either an accessible or a proxied accessible at
* the given index.
*/
AccessibleOrProxy ChildAt(uint32_t aIdx)
{
if (IsProxy()) {
return AsProxy()->ChildAt(aIdx);
}
return AsAccessible()->GetChildAt(aIdx);
}
/**
* Return the first child object.
*/
AccessibleOrProxy FirstChild()
{
if (IsProxy()) {
return AsProxy()->FirstChild();
}
return AsAccessible()->FirstChild();
}
/**
* Return the first child object.
*/
AccessibleOrProxy LastChild()
{
if (IsProxy()) {
return AsProxy()->LastChild();
}
return AsAccessible()->LastChild();
}
role Role() const
{
if (IsProxy()) {
return AsProxy()->Role();
}
return AsAccessible()->Role();
}
// XXX these are implementation details that ideally would not be exposed.
uintptr_t Bits() const { return mBits; }
void SetBits(uintptr_t aBits) { mBits = aBits; }
private:
uintptr_t mBits;
static const uintptr_t IS_PROXY = 0x1;
};
}
}
#endif